Patiently, for weeks, perhaps for months, it digs, clears and strengthens a perpendicular chimney, leaving at the surface, to keep it sequestered from the world without, a layer as thick as one’s finger. At the bottom it makes itself a recess more carefully built than the remainder. This is its refuge, its waiting-room, where it rests if its reconnoitring lead it to defer its emigration. At the least suspicion of fine weather, it scrambles up, tests the exterior through the thin layer of earth forming a lid and enquires into the temperature and the degree of humidity of the air. If things do not bode well, if a heavy shower threaten or a blustering storm—events of supreme importance when the delicate Cicada throws off her skin—the prudent insect slips back to the bottom of the tube and goes on waiting. If, on the other hand, the atmospheric conditions be favourable, then the ceiling is smashed with a few strokes of the claws and the larva emerges from the well. Everything seems to confirm that the Cicada’s gallery is a waiting-room, a meteorological station where the larva stays for a long time, now hoisting itself near the surface to discover the state of the weather, now retreating to the depths for better shelter. This explains the convenience of a resting-place at the base and the need for a strong cement on walls which, without it, would certainly give way under continual comings and goings. What is not so easily explained is the complete disappearance of the rubbish corresponding with the space excavated. What has become of the twelve cubic inches of earth yielded by an average well? There is nothing outside to represent them, nor anything inside either. And then how, in a soil dry as cinders, is the plaster obtained with which the walls are glazed? Larvæ that gnaw into wood, such as those of the Capricorn and the Buprestes, [11] for instance, ought to be able to answer the first question. They make their way inside a tree-trunk, boring galleries by eating the materials of the road which they open. Detached in tiny fragments by the mandibles, these materials are digested. They pass through the pioneer’s body from end to end, yielding up their meagre nutritive elements on the way, and accumulate behind, completely blocking the road which the grub will never take again. The work of excessive division and subdivision, done either by the mandibles or the stomach, causes the digested materials to take up less room than the untouched wood; and the result is a space in front of the gallery, a chamber in which the grub works, a chamber which is greatly restricted in length, giving the prisoner just enough room to move about.